With the heavy reliance on computing needs by businesses and individuals, the need for uninterrupted computing service has become increasingly vital. Many organizations develop business continuity plans to ensure that critical business functions will enjoy continuous operation and remain available in the face of machine malfunctions, power outages, natural disasters, and other disruptions that can sever normal business continuity.
Local disruptions may be caused, for example, by hardware or other failures in local servers, software or firmware issues that result in system stoppage and/or re-boot, etc. Local solutions may include server clustering and virtualization techniques to facilitate failover. Local failover techniques using virtualization provide the ability to continue operating on a different machine or virtual machine if the original machine or virtual machine fails. Software can recognize that an operating system and/or application is no longer working, and another instance of the operating system and application(s) can be initiated in another machine or virtual machine to pick up where the previous one left off. For example, a hypervisor may be configured to determine that an operating system is no longer running, or application management software may determine that an application is no longer working which may in turn notify a hypervisor or operating system that an application is no longer running. High availability solutions may configure failover to occur, for example, from one machine to another at a common site, or as described below from one site to another. Other failover configurations are also possible for other purposes such as testing, where failover may even be enabled from one virtual machine to another virtual machine within the same machine.
Disaster recovery relates to maintaining business continuity on a larger scale. Certain failure scenarios impact more than an operating system, virtual machine, or physical machine. Malfunctions at a higher level can cause power failures or other problems that affect an entire site, such as a business's information technology (IT) or other computing center. Natural and other disasters can impact an enterprise that may cause some, and often all, of a site's computing systems to go down. To provide disaster recovery, enterprises today may back up a running system onto tape or other physical media, and mail or otherwise deliver it to another site. When a data center goes offline for any reason, the backup data center can take over operations with the backup media. Among other shortcomings, the process of providing physical media is cumbersome, the backups have significant time intervals between one another, and recovery systems can be days out of date.